CNI chaining allows to use Cilium in combination with other CNI plugins.

With Cilium CNI chaining, the base network connectivity and IP address management
is managed by the non-Cilium CNI plugin, but Cilium attaches BPF programs to the
network devices created by the non-Cilium plugin to provide L3/L4/L7 network visibility &
policy enforcement and other advanced features like transparent encryption.